Container for storing articles at a predetermined temperature

ABSTRACT

A freight container for transporting articles at a predetermined temperature is provided with a Peltier element ( 1 ) within heat isolating walls. Under control of a control module ( 2 ), the Peltier element ( 1 ) can be energized by a battery ( 3 ) in order to collect or emit heat from/to the inside of the container. The container has an outside supporting frame that keeps the container from collapsing The Peltier element is connected to the supporting frame, via a heat spreader ( 4 ), and one or more heat pipes ( 5 ) extending through at least one of said insulating walls. Thus, the frame is used emit or collect heat to/from the outside environment of the container. The container, moreover, may comprise photovoltaic means ( 8 ) outside the container, on wall panels that are supported by the frame, for converting light into electric energy which can be fed to said Peltier element.

FIELD OF THE INVENTION

The invention relates to a freight container, such as an airfreight container and to adjustment of temperatures inside freight containers.

BACKGROUND

As is well known, commercial transport conventionally uses freight containers of standardized dimensions for the transport of freight. Aircraft freight containers for example, which need to have minimum weight, usually comprise a mechanical frame with supports such as a floor and corner profiles and cloth suspended from these corner profiles.

The transport sector has a need for methods and means for the transportation of products in a guaranteed and stable temperature environment. Important conditions for such products are: no increase of mass or volume, self-supporting (i.e. no mains needed), reliable, self regulating and without combustible, toxic or ecotoxic media. For airfreight containers, the low mass is particularly important.

In present cool box configurations no use is made of active refrigeration or heating. The performances are determined by the quality of the isolated walls (λ≈0.0042 W/mK). Alternative cool boxes, e.g. in use in the aviation, may use dry ice.

When used in a freight container, both variants have in common that the maximum admissible transportation time is determined by the internal temperature rise in the container. Use is made of a certain buffer of dry ice and/or thermal mass. If the freight container, during transportation, would have to wait for longer time in the burning sun, the maximum transportation time will be drastically restricted.

Thus, a need exists within the transport sector for a solution which comprises active cooling, which is self-supporting, reliable, self-regulating, light en small. It is an aim to provide this need.

EP 645 593 discloses a refrigerator with a Peltier element in the inner space of the refrigerator and heat pipes to couple the “hot” side of the Peltier element to cooling fins outside the refrigerator. This document is not from the field of transport containers and it does not discuss how the structural container

U.S. Pat. No. 4,981,019 discloses a portable food container that is cooled by a solar powered refrigeration unit, with a thermoelectric power unit and heat pipes. The portable food container may be used for picnics for example. This document is not from the field of transport containers that are used to load aircraft or other vehicles and it does not show that a structural container frame of such transport containers can be used in a heat control system.

US 2002/0104318 discloses a miniature cooled portable container for patients that carry cooled medicines. This document is not from the field of transport containers that are used to load aircraft or other vehicles and it does not structural container frame of such transport containers can be used in a heat control system.

SUMMARY

Among others, it is an object to provide for a freight container with active cooling, with a cooling arrangement that is self-supporting, reliable, self-regulating, light en small.

A container according to claim 1 is provided. Herein the inner space of the container is cooled with a Peltier element and heat generated by the Peltier element is conducted to the supporting container frame via a head spreader and heat pipes. Thus, the supporting frame of the container is used to get rid of heat generated by the Peltier element. In an embodiment, the supporting frame may contain wall panels, made of non-supporting material such as cloth, plastics etc, and supports, such as corner profiles, tubes or ribs, supporting the wall panels, a heat pipe being coupled to one of the supports. The connection preferably thermally bypasses the wall panels, which means that the heat pipes are not indirectly connected to the support, by a connection to a wall panel and from there to the support.

In an embodiment, the container is provided with a photovoltaic layer (for example a solar cell) to provide energy for the Peltier element. In a further embodiment the photovoltaic layer may be provided on a wall panel that is supported by the supports. In a further embodiment a heat insulation may be provided between a support that is connected to a heat pipe and an adjacent wall panel that carries a photovoltaic layer. Thus loss of efficiency of the photovoltaic layer can be reduced.

In an embodiment a container for storing articles at a predetermined temperature is provided, comprising heat insulated walls, the container comprising a Peltier element which, under control of a control module, can be energized by a battery in order to collect or emit heat from/to the inside of the container; the Peltier element being connected, via a heat spreader, to one or more heat pipes extending through at least one of said insulating walls which is connected to outside means for emitting or collecting heat to/from the outside environment of the container.

The outside means may comprise an outside container frame or a part of such frame and/or a heat conducting foil or coating, applied on the outside of at least one of said insulating walls.

Moreover, the container may comprise photovoltaic means outside the container, arranged for converting light into electric energy which can be fed to said Peltier element.

BRIEF DESCRIPTION OF THE DRAWING

These and other objects and advantageous aspects will become apparent from a description of exemplary embodiments, with reference to the following figures.

FIG. 1 shows a cross-section of a freight container

FIG. 2 shows a cross-section of a freight container

FIG. 3 shows a detail of a freight container

FIG. 4 shows a cross-section of a freight container

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a cross-section of a freight container for transporting articles stored at a predetermined temperature. The container has heat insulated walls 9, a Peltier element 1, a control module 2, a thermometer 11, a battery 3, a heat spreader 4, a plurality of heat pipes 5, an outside container frame 6, a heat conducting foil or coating 7, a photovoltaic layer 8 and a control/display unit 12. Heat insulated walls 9 surround an inside room 10 of the container, which can be filled—via a lid (not shown) with articles to be transported.

Control module 2 is coupled to Peltier element 1 and thermometer 11. Peltier element 1 can be energized, under control of control module 2 connected to a thermometer 11, by a battery 3 in order to collect or emit heat from/to the inside of the container, dependent on the actual and the desired inside temperature and the outside temperature. Peltier element 1 is connected to the plurality of heat pipes 5 via a heat spreader 4. Heat pipes 5 extend through at least one of the insulating walls 9 and are connected to outside means for emitting or collecting heat to/from (again, depending of the actual and the desired inside temperature and the outside temperature) the outside environment of the container. Instead of a plurality of heat pipes one heat pipe only may be used. Heat pipes are known per se. As is known per se, a heat pipe may be implemented as a hollow pipe that encloses an inner space with a fluid. In operation, the heat pipe provides for efficient heat transport in which the fluid may evaporate at the hot side of the heat pipe and condense at the cold side. Heat spreader 4 may be realized as a heat pipe, or a combination of a plurality of heat pipes. A planar heat pipe may be used, with box shaped walls with a planar interior space. Alternatively, heat spreader 4 may be structure such as a plane or a set of strips of heat conductive material, like aluminium, with a heat conductivity higher than that of the walls of the container.

Said outside means for emitting or collecting heat may be formed by outside container frame 6 or a part of such frame. Instead or additionally, those outside means may comprise a heat conducting foil or coating 7, applied on the outside of at least one of said insulating walls.

The electric power supply of the (self-supporting) container may be supplemented by the electrical output of photovoltaic layer 8 which is provided outside the container, and which is arranged for converting incident light into electric energy which can be fed, under control of control module 2 to the Peltier element.

A control/display unit 12 may be provided outside the container, which is arranged to switch ON/OFF the circuitry and to set/adjust the container's inside temperature; moreover, unit 12 can display the actual inside temperature, the remaining battery charge, etc.

An embodiment provides for a container for storing articles at a predetermined temperature, comprising heat insulated walls, the container comprising a Peltier element (1) which, under control of a control module (2), can be energized by a battery (3) in order to collect or emit heat from/to the inside of the container; the Peltier element being connected, via a heat spreader (4), to one or more heat pipes (5) extending through at least one of said insulating walls which is connected to outside means for emitting or collecting heat to/from the outside environment of the container. In a further embodiment said outside means comprise an outside container frame (6) or a part of such frame. Said outside means may comprise a heat conducting foil or coating (7), applied on the outside of at least one of said insulating walls. In an embodiment, the container comprises photovoltaic means (8) outside the container, arranged for converting light into electric energy which can be fed to said Peltier element.

The container preferably has a size and strength according to ISO standards for containers for loading aircraft, ships or trucks.

FIG. 2 shows a cross-section of an embodiment of a freight container in top view (not to scale), wherein the outside container frame comprises a plurality of corner supports 20, in the form of aluminium corner profiles, and on-wall supports 20 a and wall panels 22 that are supported by structural ribs 20. In addition to wall panels 22 a heat isolating wall 24 may be provided in the freight container within the space inside wall panels 22. Minimum weight wall panels 22 are preferred, especially for airfreight containers, but also for other forms of transport. Wall panels made of cloth, or other flexible sheet material may be used for example, that hangs from the supports 20, 20 a. Other types of panels with a more permanent shape may be used. In this embodiment, heat pipes 5 are connected between supports 20, 20 a and heat spreader 4. The photovoltaic layer (not shown) is provided on wall panels 22. By using the different constructive elements of the freight container, such as supports 20, 20 a and wall panels 22 for energy dissipation and energy generation for temperature adjustment, i.e. for different functions in temperature control, more efficient operation may be realized.

In principle, each support 20, 20 a may be coupled to heat spreader 4 via one or more heat pipes 5. But usually it will suffice to couple only part of supports 20, 20 a to heat spreader 4 via one or more heat pipes 5. An external heat spreader such as a heat pipe (not shown) may be provided on a support 20, 20 a outside heat isolating wall 24, to spread heat more efficiently over the support 20, 20 a.

When heat pipes to supports 20, 20 a on a plurality of faces of the container are used, heat spreader 4 may likewise extend along a plurality of faces. Although an embodiment with on-wall supports 20 a located midway between successive corners of the container are shown, it should be appreciated that these may be left out in smaller containers. For larger containers a plurality of on-wall supports 20 a may be used on the same face of the container. Although not visible in the cross-section in top view, it should be appreciated that horizontal supports (not shown) may further be present at the top and/or bottom of the container, or in between top and bottom, connecting the ends of pairs of corner supports 20 and optionally on-wall supports 20 a. Corner supports 20 and optional on-wall supports 20 a may extend from the top to the bottom, preferably between such horizontal supports. Heat pipes 5 connected between the heat spreader 4 and the horizontal .supports may be used in the container instead of, or in addition to the heat pipes to the corner supports 20 and/or on-wall supports 20 a.

Similarly, the photovoltaic layer (not shown) may be provided on all wall panels 22, but it may suffice to provide the photovoltaic layer only on part of the wall panels 22. Preferably, photovoltaic layers are provide on a plurality of wall panels 22 that face in mutually different directions, this reduces dependence on the side of the freight container that is exposed to light.

FIG. 3 shows an embodiment of the freight container in more detail. In this embodiment a heat insulating layer 30 is provided between corner support 20 and wall panel 22. By heat insulating layer 30 it is meant that the heat insulating layer 30 has a lower thermal conductivity than structural ribs 6 per unit area and over the same thickness. Heat insulating layer 30 reduces efficiency loss of photovoltaic layers 8 on wall panels 20 due to heating of photovoltaic layers 8 from structural ribs 20. Heat pipe 5 connects to corner support 20 through, or around heat insulating layer 30.

FIG. 4 shows a lateral cross-section of an embodiment of a freight container wherein heat pipes 5 are connected between heat spreader 4 and a floor support 40 of the container. Floor support 40 provides a floor on which the remainder of the container rests. Floor support 40 may be may be made of aluminium or of another metal or heat conducting material for example. Floor support 40 may be provided with spacers to keep an open space between part of floor support 40 and an underlying floor for entering the fork of a fork lift truck. By using the floor support 40 of the container, it is made possible to cool a container with self-supporting wall panels 22, without corner supports. Instead of “supports”, corner supports 20, on-wall supports 20 a and floor support 40 may be called support elements, the word support(s) signifying that the support(s) or support elements have a mechanically supporting function, supporting wall panels, other supports or the weight of the container for example. Floor support 40 may form the floor of the container itself, or an additional floor may be provided on floor support 40.

The container may be an airfreight container for example. Standard dimensions have been defined for such containers, aircraft being provided with loading bays of corresponding dimensions size into which containers of the standardized dimensions. One standard of airfreight dimensions is the LD3 standard, for example. The cross section of FIG. 4 shows an obliquely cut-off corner of one type of standard airfreight container, adapted to the shape of aircraft loading bays.

Although embodiments have been described wherein Peltier element 1 is used for cooling the inside of the container, it should be appreciated that alternative Peltier element 1 may also be used for heating. Thus, for example, if the outside temperature of the container is high, Peltier element 1 may be used for cooling, and when the outside temperature of the container is low, Peltier element 1 may be used for heating.

Preferably, temperature regulation to a predetermined temperature inside the container is used. However, it should be appreciated that instead adjustment of the temperature by the action of Peltier element to within a predetermined temperature range may be used. In this embodiment power needs to be supplied only when temperature inside the container threatens to move outside this temperature range. Thus, the amount of required cooling and/or heating may be reduced.

Although an embodiment with a single Peltier element 1 has been shown, it should be appreciated that a plurality of such elements may be used, located at mutually different positions in the container, each coupled to the outside of the container, such as to structural ribs 6 via heat spreader 4 and heat pipes 5. 

1. A transport container for transporting articles, the container comprising heat insulating walls; a container frame outside the heat insulating walls; a Peltier element (1) within the heat insulating walls; a heat spreader (4) coupled to the Peltier element (1) within the heat insulating walls; at least one heat pipe (5) connected from the heat spreader (4) to the container frame and extending through at least one of said insulating walls.
 2. A transport container according to claim 1, wherein the container frame comprises a support (6, 20, 20 a, 40) and a wall panel (22) supported by the support (6, 20, 20 a, 40), at least one of the heat pipes (5) being connected from the heat spreader (4) to the support (6, 20, 20 a, 40).
 3. A transport container according to claim 2, wherein said support to which said at least one of the heat pipes (5) is connected is a corner support (20), extending vertically from a floor of the container at a corner of the container, and/or an on-wall support (20 a) extending vertically from a floor of the container along a wall of the container.
 4. A transport container according to claim 3, wherein said support to which said at least one of the heat pipes (5) is connected is a floor panel of the container.
 5. A transport container according to claim 1, wherein the container is a freight container.
 6. A transport container according to claim 1, wherein the container is an airfreight container having standardized dimensions for loading into aircraft.
 7. A transport container according to claim 2, comprising a photovoltaic layer (8) on the wall panel, facing outside the container and coupled to said Peltier element for supplying electric energy to the Peltier element.
 8. A transport container according to claim 7, comprising a plurality of wall panels, photovoltaic layers (8) on said plurality of the wall panels respectively, facing outside the container in mutually different directions from the container, coupled to said Peltier element for supplying electric energy to the Peltier element.
 9. A transport container according to claim 7, comprising a battery, the photovoltaic layer (8) or photovoltaic layers being coupled to said Peltier element via the battery.
 10. A transport container according to claim 7, comprising a heat insulating layer between said support and the wall panel on which the photovoltaic layer is provided.
 11. A transport container according to claim 1 comprising a control module (2), and a battery (3) the control module being configured to energize the Peltier element from the battery (3) in order to collect or emit heat from/to the inside of the container.
 12. A transport container according to claim 11, said outside means comprising a heat conducting foil or coating (7), applied on the outside of at least one of said insulating walls.
 13. A method of transporting articles in a container, the method comprising cooling an interior space of the container with a Peltier element in the interior space and transporting heat generated by the Peltier element from the Peltier elements to a supporting container frame via a heat spreader (4), and heat pipes (5) coupled between elements of the container frame and the heat spreader.
 14. A method according to claim 13, wherein the container has standardized dimensions for loading into an aircraft load bay, the method comprising fitting the container into an aircraft load bay space dimensioned to correspond to said standardized dimensions. 